The scroll compressor has become widely accepted in home and commercial air conditioning systems. In such a compressor, two scroll elements, each having a wrap, are driven so that one scroll element is in orbital motion relative to the other. A series of constantly changing compression pockets are formed between the interacting wraps of the scroll elements that act to compress a refrigerant gas therebetween. Generally, the gas is compressed in moving radially inward from the outer perimeter of the scroll elements to the center thereof.
As the scroll compressor is operated, forces are exerted which urge the scroll elements apart axially along the axis of orbital motion between the scroll elements. This force is commonly resisted by bleeding compressed refrigerant gas from a compression pocket between the wraps of the scroll elements to a chamber formed behind one of the scroll elements. The pressure in the chamber acts on the base of the scroll element to force the scroll elements together. Seals are used to isolate this chamber from the interior of the scroll compressor, which is usually at either the suction or the discharge pressure in the compressor. In one application of this approach, the seals and chamber are located behind the moving, or orbiting scroll. In addition to the sealing action, this design also requires the seals to withstand the sliding action of the orbiting scroll as well as imposing a sliding friction force between the seal and scroll.
While adequate seals have been developed for this purpose, a number of disadvantages exist. One disadvantage is the relatively high starting torque requirement placed on the motor in the compressor in initial start up to overcome the friction between the seal and scroll necessitated by sufficient seal forces to maintain the desired sealing action during the starting transient. The seal forces must be sufficient to maintain the desired sealing action as the compressor is in the starting transient and only a tiny amount of compressed gas is available from the pressure vent to actuate a seal. Other shortcomings are the cost of the seals and providing a sufficient range of motion to the scroll elements while maintaining sealing engagement. A need exists for improved seals which eliminate these disadvantages.